1. Field of the Invention
The present invention relates generally to a numerical control system for machines, and more particularly to a pulse distribution apparatus for distributing drive pulses to drive servomechanisms in such a system so as to displace thereby a movable member along a line segment to be linearly interpolated.
2. Description of the Prior Art
In one known pulse distribution method for linear interpolation, there is first made a decision as to whether a transient position of a movable member which is displaced along both X and Y-coordinate axes is present within the plus (+) area or the minus (-) area with respect to a line segment to be linearly interpolated and then, one drive pulse whose frequency is controlled in accordance with a commanded feed rate is distributed to either of the X and Y-axis directions depending upon the result of the decision. Therefore, it is necessary to carry out one operation each time one pulse is outputted, and the locus approximated by the method becomes stepped, undesirably inviting large error as well as lacking smoothness. Moreover, as the frequency of the drive pulse is controlled faithfully in agreement with the feed rate, the resultant feed rate undesirably fluctuates depending upon the slope of the line segment to be interpolated.